protists
DESCRIPTION
Protists. Eukaryotes w/o tissue level of organization as in animals, plants, and fungi. Generalizations. Most unicellular Organelles that are similar to eukaryote animals None have embryonic tissue layers as in animals. Classification of Protista:. Excavata Diplomonadida = Giardia - PowerPoint PPT PresentationTRANSCRIPT
Generalizations
Most unicellular
Organelles that are similar to eukaryote animals
None have embryonic tissue layers as in animals
Classification of Protista:
Excavata Diplomonadida = Giardia Kinetoplastida = trypanosomes Euglenida = Euglena
Alveolata & Chromista Ciliophora = ciliates Apicomplexa = gregarines, coccidians Dinoflagellata = flagellates Opalinida = Opalina
Classification of Protista:
Rhizaria Rhizopoda = amoebas Actinopoda = radiolarians
Amoebozoa Lobosea = amoebas
Opisthokonta Chlorophyta = Volvox
Support and Locomotion
Plasma membrane Many have thickening = pellicle Or a test
Pseudopodia, cilia, flagella
Nutrition
Autotrophs = ? Heterotrophs = ? Or both
Saprobic = take in dissolved stuff Holozoic = solid foods (food vacuole)
Sexual repro
Production of gametes and then fusion = syngamy
Isogamy = same size gametes Anisogamy = one larger
Or conjugation
Phylum Euglenida
Mostly freshwater, few marine, brackish
Usually in habitat w/decaying organic matter
2/3 euglenids w/o chloroplasts = heterotrophs = phagocytosis Others can lose chloroplasts and switch
Few parasitic forms
Saprotrophic = take in dissolved nutrients
Phylum Kinetoplastida
Trypanosomes, etc. ~ 600 species described Some free-living
Trypanosomes strictly parasitic Digestive tracts of invert’s, phloem of plants,
blood of vert’s
Other parasitic forms Leishmania: transmitted by sandflies Causes skin and mucous membrane
infections in humans
T. gambiense, others = sleeping sickness Tse-tse fly is intermediate host Tryps get into blood, then lymphatics and CS
fluid
Support, locomotion
Pellicle, glycoprotein protects outside
Flagella: single, against side of cell
nucleus
kinetoplastkinetosome
Nutrition
Mostly unknown in parasitic forms
Free-living spp. are heterotrophic; capture bacteria with flagellum
Infection occurs when infected sandfly regurgitates infective promastigotes into the blood while feeding.
The promastigotes are phagocytized by macrophages and transform into amastigotes.
The amastigotes multiply by binary fission in the macrophages.
The life cycle is continued when a sandfly feeds on an infected person and ingests the amastigotes in the macrophages.
Phylum Ciliophora ~ 12,000 described species
Common in benthic, planktonic communities
Freshwater, marine, brackish
Most are single celled
Mutualistic symbionts
E.g., in goats, sheep Feed on plant material
Some are parasites in fish gut, one in human gut
Support, locomotion
Alveolar membrane system Underlying fibrous layer = epiplasm
Cilia in rows; used in taxonomy More flexible for locomotion than flagella Beat in cone